Air carrier X had less than standard separation from air carrier Y. System error.

Attributes
ACN	156435
Time
Date	199009
Day	Thu
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : dqn
State Reference	OH
Altitude	msl bound lower : 29000 msl bound upper : 29000
Environment
Flight Conditions	IMC
Light	Night
Aircraft 1
Controlling Facilities	artcc : zid
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other
Flight Phase	cruise other
Route In Use	enroute : on vectors
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other
Flight Phase	descent other other
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Experience	controller non radar : 3 controller radar : 1
ASRS Report	156435
Person 2
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Events
Anomaly	conflict : airborne less severe non adherence : required legal separation non adherence : published procedure
Independent Detector	atc equipment other atc equipment : unspecified other controllera
Resolutory Action	controller : issued new clearance other
Consequence	faa : investigated
Miss Distance	horizontal : 12000 vertical : 200
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error

Narrative:

Air carrier X was at FL290 holding west on the 290 right of the dqn VORTAC. Air carrier Y was an overflt from stl to pit at FL290. Air carrier Y was not idented as traffic for air carrier X as he entered the sector well south and was eastbound. Several other aircraft were also in confliction and required my immediate attention. When these were resolved a review of air carrier Y and air carrier X situation indicated action needed to be taken but vertical sep could not be gained before lateral sep was lost. Callback conversation with reporter revealed the following information. The reporter stated he thought air carrier Y would pass south of the holding pattern. The computer plot after the incident air carrier Y was drifting toward the holding pattern which the reporter failed to recognize. Position relief took place and the relieving controller had been working the position 1 min prior to the loss of sep between air carrier X and Y. Air carrier X was descended and air carrier Y was turned. Conflict alert activated at the same time edp went off.

Original NASA ASRS Text

Title: ACR X HAD LESS THAN STANDARD SEPARATION FROM ACR Y. SYSTEM ERROR.

Narrative: ACR X WAS AT FL290 HOLDING W ON THE 290 R OF THE DQN VORTAC. ACR Y WAS AN OVERFLT FROM STL TO PIT AT FL290. ACR Y WAS NOT IDENTED AS TFC FOR ACR X AS HE ENTERED THE SECTOR WELL S AND WAS EBND. SEVERAL OTHER ACFT WERE ALSO IN CONFLICTION AND REQUIRED MY IMMEDIATE ATTN. WHEN THESE WERE RESOLVED A REVIEW OF ACR Y AND ACR X SITUATION INDICATED ACTION NEEDED TO BE TAKEN BUT VERT SEP COULD NOT BE GAINED BEFORE LATERAL SEP WAS LOST. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO. THE RPTR STATED HE THOUGHT ACR Y WOULD PASS S OF THE HOLDING PATTERN. THE COMPUTER PLOT AFTER THE INCIDENT ACR Y WAS DRIFTING TOWARD THE HOLDING PATTERN WHICH THE RPTR FAILED TO RECOGNIZE. POS RELIEF TOOK PLACE AND THE RELIEVING CTLR HAD BEEN WORKING THE POS 1 MIN PRIOR TO THE LOSS OF SEP BTWN ACR X AND Y. ACR X WAS DSNDED AND ACR Y WAS TURNED. CONFLICT ALERT ACTIVATED AT THE SAME TIME EDP WENT OFF.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.